RT Journal Article SR Electronic T1 Babesiosis as a cause of false-positive HIV serology JF BMJ Case Reports FD BMJ Publishing Group Ltd SP bcr-2017-223738 DO 10.1136/bcr-2017-223738 VO 2018 A1 Mariola Smotrys A1 Tara Magge A1 Samer Alkhuja A1 Susheer Dilbagh Gandotra YR 2018 UL http://casereports.bmj.com/content/2018/bcr-2017-223738.abstract AB This is a case of a 71-year-old homosexual man who presented with a 4-day history of fever, weakness and headaches, near syncope, nausea and poor oral intake. The patient denied recent travel or sick contacts but had significant tick bites in the last 4 weeks. A peripheral blood smear showed 0.5% parasitaemia with signet ring appearance organisms consistent with Babesia microti. Serology testing for HIV 1 and 2 by ELISA and western blot were positive. Treatment for Babesia was started and the patient improved. Repeat serology testing for HIV was negative. To the best of our knowledge, this is the first case of false-positive HIV serology that is associated with active babesiosis. In this case, the positive HIV serology turned negative after successful treatment of babesiosis.